During New Student Week, you probably planted a tree sapling somewhere in the Arb. You may have given it a name, noted its location, and hoped to visit it many years later. But have you ever wondered how it manages to get through its first winter—facing snow, wind, and freezing temperatures?

The first few winters after a sapling is planted are crucial to its long-term survival, especially in Minnesota’s cold, dry climate. Newly planted trees lack established root systems, have low energy reserves, and are more vulnerable to winter desiccation and cold injury. Repeated freezing and thawing causes soil to expand and contract, which can push saplings out of the ground (frost heaving). 

Over time, trees become more resilient, developing deeper roots, stronger bark, and larger energy reserves. If a sapling can make it through the first few winters successfully, it’s likely to endure many more for the rest of its life. 

This year in the Arb, students planted red, white, and bur oaks—trees that are well-adapted to Minnesota’s winters. In the fall, they drop their leaves to conserve water and energy. In the winter, they enter a dormant period during which they stop actively growing and slow down many cellular processes to conserve resources. To prevent intracellular freezing, they increase sugar concentration in cells, which acts like natural antifreeze. 

The biggest factors affecting sapling survival are planting technique (proper depth), water availability, and competition from other plants. To help NSW trees survive their first year, Arb staff water them through the fall to make sure there is adequate soil moisture, use mulch mats to maintain moisture and reduce competition, and place rabbit guards, tubes, and leaf bags to protect the trees from herbivores. 

Not every sapling makes it through the winter. Depending on the year, about one-quarter of trees planted during New Student Week won’t survive—and mortality is especially high in drought conditions. However, with proper care and just the right amount of luck, there’s a good chance you’ll see your tree flourishing decades down the line.